20 Aug
2010
20 Aug
'10
9 p.m.
On 08/20/2010 01:43 PM, Tony Duell wrote:
Really they did!
> On Fri, Aug 20, 2010 at 6:35 AM, Tony Duell<ard
at p850ug1.demon.co.uk> wrote:
>
>
>> What do you consider the DPP11/23 and PDP11/73 to be? (Remember the CPU is
>> a small number of custom LSI chips).
>>
>>
The F11 cpu was considered a microcomputer (PDP-11/23 cpu) as
are the first in that line the LSI-11, also J11, and T-11. That was
DECs designation.
However be careful as DEC systems could be mini or larger in scope built
with microprocessers. MicroVaxII is a an example as would be the
VAX6000.
Never fear,
the DEC marketing crowd "fixed" that one too, they were
"Supermicrosystems", as per the handbook (1986) which covered the MicroVAX
I,II, Micro PDP11/23,73,83.
OK :-)
But DEC had their own meaning for
'microprocessor' to mean a 'microcoded
control system'. I seem to remember that the control logic of a VT52 and
that of the DMC11, etc are called 'microprocessors' in the DEC manuals,
for all the are built from lots of MSI chips, and there's nothing that
the rest of the world would call a microprocessor (a chip such as a Z80,
6800, 8080, 6502, etc)
Ah, not quite. I say that as an ExDEC. There are two problems with
the statement one is when and how the terms were used. When is
very important as it was both the appearance of common use and
the application of it to DEC machines. The how is also the same
thing really but the actual application by others or adoption by marketing
In the early days about 1974 maybe a bit before, it usually implied
microcoded processor or state machine. VT52 never had a CPU
of any form it was all state machine in microcode and random logic.
The first DEC terminal with a CPU actually microcomputer was Vt100.
After the 8080 microprocessor tended to mean a cpu on one chip
or very few for example CDP1800/1801 a two chip predecessor
of the COSMAC CDP1802.
The whole mini- thing started in the exact time frame as the
appearance in the USA of the embarrassing short skirts aptly
named miniskirts. It was a magazine that connected PDP-8 with
mini-computer. It was about 1965-66 that computer packaging
to table top or desk side size was making relatively small machines
like the CDC160 and others. However the mini-attribution was not
assigned to the later generation about the time of the PDP-8i.
The PDP8 was a instruction and mostly compatible but improved
follow on to the all transistor PDP-5 (1963) but much larger than
the first version of the PDP-8 by a factor of three racks. Note the
PDP-5 was almost as large as the PDP1 but was aimed at lower
cost to buy and use.
Also when referring to the PDP-8 a specific machine and family
designation that reaches from 1965 to late 80s and includes
the -8, -8s, -8i, -8e and -8a as major varients of the same design.
However the 8e/f/m version with the Omnibus was the longest running
and highest volume member with the 8a also using he same bus.
The 8f was the smallest of the 8e family with a full front panel
but still having expansion space. The 8a was smaller but lacked
the traditional lights and switches panel.
The demarcation of mini and micro really started to happen in
the mid 70s with CPU on a chip (8080, 6800, 6502 et al).
From a point of view of say 1978.. we called them like this.
PDP-1 was most notable not for small but cheap (relatively) at
under 1,000,000$ (those are 1960 Dollars!).
PDP1 not really classed back then it was considered BIG
and big meant needs forklift to move.
PDP10 mainframe as we IBM 360/370 and Univac1108
PDP8 mini
PDP11 mini, as well as DG nova and CM2000,2100, 2200 series
*by 1972 the number of companies making distinct
machines in the 12/16 bit class was large.
LSI-11 was microcomputer
VAX11/780 first superminicomputer. VAX early on was the 32bit
next step from PDP11 and included compatability mode with PDP-11
to exploit the large pdp-11 base and it's migration to 32bit platform.
See:
ftp://rtfm.mit.edu/pub/usenet/alt.sys.pdp8/PDP-8_Frequently_Asked_Questions…
Allison
-tony